It was a match in the Carabao Cup which I don't think was a problem even if Manchester City lost, because it looks like Manchester City is currently improving its performance to be able to come back strong in the Premier League. Because Manchester City's performance this season in my view has slightly decreased, so Manchester City's defeat by Southampton in the Carabao Cup event is proof that Manchester City at this moment does have a problem.
Manchester City's defeat in the Carabao Cup actually surprised me a bit because at first I thought Manchester City would easily reach the final. But in reality, the Manchester City players chose to play more carefully than push themselves to win and put up a better fight. Southamton put more pressure on the Manchester City players with some tough tackles and did not hesitate to do so only to keep the players from developing their game. In this situation, Southamton benefits because Manchester City prefers to play it safe and avoid injury because there is a more important match than the Carabao Cup.
What's more, Manchester City also has to consider good gameplay to play in the Champions League, so yes, maybe not many can accept the defeat. But for me, Manchester City's defeat by Southampton in the Carabao Cup is a final result that still makes sense.
I don't think Manchester City's performance was bad enough that game, but they just didn't really play to win when Southamton looked to threaten them physically. This is a good strategy to stop Manchester City, it has forced Manchester City to play wider than usual. Southamton next meet Newcastle and I'm sure they will lose.